21420433 has 2 divisors, whose sum is σ = 21420434. Its totient is φ = 21420432.

The previous prime is 21420403. The next prime is 21420439. The reversal of 21420433 is 33402412.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 12759184 + 8661249 = 3572^2 + 2943^2 .

It is a cyclic number.

It is not a de Polignac number, because 21420433 - 2¹⁷ = 21289361 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21420433.

It is not a weakly prime, because it can be changed into another prime (21420439) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10710216 + 10710217.

It is an arithmetic number, because the mean of its divisors is an integer number (10710217).

Almost surely, 2^21420433 is an apocalyptic number.

It is an amenable number.

21420433 is a deficient number, since it is larger than the sum of its proper divisors (1).

21420433 is an equidigital number, since it uses as much as digits as its factorization.

21420433 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 576, while the sum is 19.

The square root of 21420433 is about 4628.2213646281. The cubic root of 21420433 is about 277.7214443215.

Adding to 21420433 its reverse (33402412), we get a palindrome (54822845).

The spelling of 21420433 in words is "twenty-one million, four hundred twenty thousand, four hundred thirty-three".